Organic electroluminescent devices (OLEDs) typically includes one or more light emitting layers disposed between two electrodes, e.g., a cathode and a light transmissive anode, formed on a light transmissive substrate. The light emitting layer emits light upon application of a voltage across the anode and cathode. Upon the application of a voltage from a voltage source, electrons are directly injected into the organic layer from the cathode, and holes are directly injected into the organic layer from the anode. The electrons and the holes travel through the organic layer until they recombine at a luminescent center. This recombination process results in the emission of a photon, i.e., light. Large area OLED devices typically combine many individual OLED devices on a single substrate or a combination of substrates with multiple individual OLED devices on each substrate. Applications for large area OLED devices include area lighting.
Electroluminescent layer patterning has been conventionally performed using stamping or laser ablation. In stamping, a pattern is imprinted upon the layer using mechanical force upon a patterned die or a stamping head, whereas in laser ablation, a patterned photomask covers the area to be patterned while the remaining area is selectively etched using a laser beam. Another approach includes inkjet printing.
A recent attempt for applying the patterned active electroluminescent layer is disclosed in U.S. Patent Application Publication No. 2005/0129977 by Poon et al., which includes a combination of a web coating using a roller having an elongated coating surface such as a micro gravure coating process and a solvent assisted wiping process for removing portions of the applied active electroluminescent web coated layer. U.S. Pat. No. 7,049,757 discloses an array of light devices connected in series.
Organic photovoltaic (OPV) devices may be fabricated using similar materials and concepts as the OLED devices. Organic photovoltaic (OPV) devices typically include at least two layers of organic semiconducting materials disposed between two conductors or electrodes. At least one layer of organic semiconducting material is an electron acceptor, and at least one layer of organic material is an electron donor. An electron acceptor is a material that is capable of accepting electrons from another adjacent material due to a higher electron affinity of the electron acceptor. An electron donor is a material that is capable of accepting holes from an adjacent material due to a lower ionization potential of the electron donor. The absorption of photons in an organic photoconductive material results in the creation of bound electron-hole pairs, which must be dissociated before charge collection can take place. The separated electrons and holes travel through their respective acceptor (semiconducting material) to be collected at opposite electrodes.
There is a need for further deposition and patterning techniques in the fabrication of organic electronic devices.